One of the promising ways to overcome the intermittency of renewable energy sources is to utilize a largescale thermal energy storage system. The recent research and development of TES systems have suggested increasing the design temperature to obtain higher efficiency. In this research, analyses were conducted on the current status and behavior characteristics of heat resistant candidate materials used in pressure boundary components and piping systems in large-scale thermal energy storage performance test facilities, using a design temperature of 700 degrees C. Comparative analyses were conducted on the material behaviors of candidate materials, such as the creep rupture strengths and design stress intensities of the codified materials in the design rules of nuclear-grade and non-nuclear-grade; because the facility was operating at high temperatures, thereby requiring high levels of reliability. In addition, analyses on the absent material properties in the design rules from a 700 degrees C high-temperature design evaluation viewpoint, were conducted, where some of the absent material properties were obtained from material tests.
